1. Field of the Invention
The present invention relates to an apparatus, system and methods of administering a fluid such as a medicated fluid in metered amount such as a unit dose to treat respiratory ailments. In particular, the invention relates to disposable aerosol generators, wherein the aerosols are generated via vaporization.
2. Description of Related Art
Aerosols are useful in a variety of applications including treatment of respiratory ailments. Various techniques for generating aerosols are disclosed in U.S. Pat. Nos. 4,811,731; 4,627,432; 5,743,251; and 5,823,178.
In particular, two distinct methods for delivery of medicated fluid in the form of an aerosol have been developed. In accordance with one method, a pharmaceutically active drug is dispensed in a low boiling point propellant (e.g., chloro-fluoro-carbon (CFC) or (HFA)) loaded in a pressurized canister from which the drug/propellant formulation may be released by the use of a device generally known as a metered dose inhaler. Once released the propellant evaporates and particles of the drug are inhaled by the patient. The other method involves the use of a nebulizer which creates an inhalable mist of fine particles from a solution or suspension of a drug. Both methods are hindered by significant problems relating to administering the proper dose.
In drug delivery applications, it is typically desirable to provide an aerosol having average mass median particles diameter of less than 2 microns to facilitate deep lung penetration. Additionally, it is desirable, in certain drug applications, to deliver medicaments at high flow rates (i.e., above 1 milligram per second). Devices for controlling the flow rate of an aerosol are known. For example, U.S. Pat. No. 4,790,305 concerns controlling the particle size of a metered dose of aerosol for delivery to the walls of bronchi and bronchioles by filling a first chamber with medication and a second chamber with air such that all of the air is inhaled prior to the inhaling medication, and using flow control orifices to control the flow rate. U.S. Pat. No. 4,926,852 relates to metering a dose of medication into a flow-through chamber that has orifices to limit the flow rate to control particle size. U.S. Pat. No. 3,658,059 discloses a baffle that changes the size of an aperture in the passage of the suspension being inhaled to select the quantity and size of particles delivered. A problem associated with these devices is that they process the aerosol after it is generated and are inefficient and wasteful.
To meet the requirements of administering a fluid in the form of an aerosol and to overcome the disadvantages of the prior art, it is an object of the present invention to provide an aerosol generator which vaporizes the fluid at a controlled flow rate regardless of the fluid's viscosity.
It is another object of the invention to obtain uniform vaporization of the fluid that is expelled from the aerosol generator.
It is a further object of the invention to provide a disposable aerosol generator which can deliver a metered dose of the fluid. By delivering individual single doses of medicated fluid it is possible to avoid contamination of the fluid, thereby negating the need for bacteriostatic compounds within the drug formulation.
It is yet another object of the invention to provide a disposable cartridge which can incorporate a package having therein multiple disposable aerosol generators, each of which provides a single shot delivery, as required by the user.
Other objects and aspects of the present invention will become apparent to one of ordinary skill in the art upon review of the specification, drawings and claims appended hereto.